Search Results (81)

The plastisphere can have a significant impact on the buoyancy, toxicity, and functionality of microplastics (MPs). Little is known about plastisphere structure, especially in salt-impacted lakes, despite the growing focus on the salinization of lakes. Virgin polypropylene and polyethylene terephthalate MPs were incubated for two weeks in flow-through containers in the epilimnion (low phosphorus, low salinity, high light) or hypolimnion (high P, high salinity, and low light) of a salt-impacted lake and then incubated in the lab in either their original water or water from the alternate depth to determine plastisphere response should the lake fully turn over. Environmental factors, including phosphorus concentration, light level, salinity level, and temperature, rather than polymer type, influenced community composition. Bacterial communities on MPs in the epilimnion exhibited higher diversity compared to those in the hypolimnion. Algal communities on MPs showed a similar trend, with greater diversity in the epilimnion. Overall, initial community composition had a stronger influence on community structure (priority effect) than the environment in which the plastisphere was grown. For those plastisphere communities capable of responding to species-specific desirable environmental conditions, lake mixing that results in increases in phosphorus and salinity from the hypolimnion to the epilimnion will increase the abundance of algae on MPs in the photic zone. Full article

This study investigates the influence of surface-modified fly ash particles on the fire behavior of polyamide 6 (PA6) composites containing two types of flame retardants: melamine polyphosphate (MPP) and aluminum diethyl phosphinate (AlPi). The objective was to evaluate how interfacial modification of fly ash using amino-silane (APTES), glycidoxy-silane (GPTES), or titanate coupling agents affects dispersion, thermal stability, and combustion performance. A series of 18 formulations containing up to 25 wt% of additives was prepared by melt compounding and characterized by thermogravimetric analysis (TGA) and cone calorimetry. TGA results showed that MPP-based systems favored char formation, with residues up to 21%, whereas AlPi provided higher thermal stability (T₅₀% ≈ 445 °C). The incorporation of untreated or surface-treated fly ash improved both thermal stability and char yield, depending on the nature of the coupling agent. Cone calorimeter results confirmed a strong synergistic effect between flame retardants and fly ash. The peak heat release rate (pHRR) decreased by 65–75% compared to neat PA6, while total heat release (THR) and mass loss were also significantly reduced. Titanate-modified fly ash showed the most homogeneous dispersion and provided the highest residue and lowest pHRR values. Energy-dispersive X-ray (EDX) analyses confirmed enhanced phosphorus retention in the residues (up to 100%), evidencing the formation of stable inorganic species and protective ceramic-like structures. These results demonstrate that surface-modified fly ash can act as an efficient synergistic additive in PA6 flame-retardant formulations, simultaneously improving fire performance and promoting the valorization of industrial by-products for sustainable polymer design. Full article

Phytic acid (myo-inositol hexakisphosphate) and its salts, including iron, aluminum, sodium, and lanthanum phytate, are perhaps the most recent discovery in the field of bio-sourced flame retardants. Phytic acid can be extracted from sustainable resources, such as beans, cereals, and oilseeds. Its high phosphorus content (28 wt.% based on molecular weight) organized into six phosphate groups justifies the growing interest this biomolecule has attracted over the last decade in various sectors (as a corrosion inhibitor, antioxidant, and anticancer additive, among others). In addition, when exposed to a flame or an irradiative heat flux, phytic acid is a highly efficient dehydrating and char-forming agent. It also contributes to excellent flame-retardant properties when combined with other carbon sources, such as chitosan, or nitrogen-containing additives, including melamine, urea, and polyethyleneimine. This paper reviews the most recent advances in using phytic acid and its derivatives to design effective flame-retardant systems for textiles, bulk polymers, and foams. It also provides perspectives on possible future developments and implementations. Full article

Phosphogypsum (PG) is a byproduct of wet-process phosphoric acid production and contains soluble phosphorus (P), fluorine (F), and other harmful impurities in addition to calcium sulfate. Its acidic leachate enriched with P and F poses long-term risks to soil and surrounding water bodies. Owing to the incorporation of soluble P and F within calcium sulfate crystal interlayers, these contaminants are gradually released during storage, making it difficult to achieve an economically efficient and environmentally benign treatment of PG at an industrial scale. In this study, a low-cost and sustainable process for the effective and long-term immobilization of soluble P and F in PG was developed using sulfuric acid-activated red mud (RM), an industrial waste rich in Fe and Al. After pulping PG with water, activated RM was added, followed by pH adjustment with Ca(OH)₂, leading to the in situ formation of amorphous calcium aluminate and calcium ferrite polymers with strong adsorption affinity toward soluble P and F. The immobilization mechanism and phase evolution were systematically investigated using inductively coupled plasma optical emission spectroscopy (ICP-OES, PS-6PLASMA SPECTROVAC, BAIRD, USA), on a Rigaku Miniflex diffractometer (Rigaku Corporation, Tokyo, Japan), scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), and zeta potential analysis. The leachate of PG treated with activated RM and Ca(OH)₂ contained P < 0.5 mg/L and F < 10 mg/L at pH 8.5–9.0, meeting environmental requirements (pH = 6–9, P ≤ 0.5 mg/L, F ≤ 10 mg/L). Moreover, the immobilized P and F exhibited enhanced stability during long-term stacking, indicating the formation of durable immobilization products. This study demonstrates an effective “treating waste with waste” strategy for the large-scale, environmentally safe utilization of phosphogypsum. Full article

Porous highly cross-linked polymer (PIP) was synthesized by a polycondensation reaction between hexachlorocyclotriphosphazene and piperazine. The obtained polymer has a surface area of 76.9 m²/g and a mesoporous structure. After carbonization, the obtained product (PIP-C) has a surface area of 177 m²/g. The obtained carbon product contained nitrogen and phosphorus heteroatoms, which leads to a higher specific capacitance (155.6 F/g) and catalytical activity in the electroreduction of oxygen (15.9 A/g). This work shows the possibility of the use of such porous phosphazene polymers as precursors for heteroatom-doped carbon materials, which might be used in electrochemical devices like electrodes for supercapacitors or metal-free electrocatalysts in fuel cells. Full article

Flame-retardant microcapsules were prepared using a urea–melamine–formaldehyde (UMF) shell and boric acid-crosslinked ammonium polyphosphate (APP) as the core to improve the dispersion stability and processing compatibility of phosphorus-based flame retardants. Thermal analysis showed that the microcapsules exhibited initial mass loss near 80 °C due to moisture evaporation and shell relaxation, while APP-related degradation occurred at higher temperatures, indicating delayed release of the core and enhanced thermal resistance through encapsulation. Scanning electron microscopy confirmed the formation of microcapsules, and morphological changes before and after combustion suggested the development of protective char layers. Boron-containing residues are expected to contribute to char stabilization through the formation of B–O–P structures during heating. The flame-retardant properties were evaluated using limiting oxygen index, smoke density, and vertical burning tests. Although the limiting oxygen index slightly decreased due to reduced accessible APP content, stable burning behavior was maintained, and characteristic char formation was observed after combustion. These results indicate that the UMF/APP microcapsules can improve thermal stability and handling of phosphorus-based flame retardants. The microencapsulation approach presented here may provide practical advantages for polymer processing and surface-coating applications. Full article

Phosphorus-modified poly(vinyl alcohol) (PVA) has recently gained increasing attention as a functional polymeric matrix suitable for gel-based systems, owing to its biocompatibility, film-forming ability, and capacity to develop semi-interpenetrating networks. In this work, PVA was chemically modified through the nucleophilic substitution of its hydroxyl groups with the chloride groups of phenyl dichlorophosphate, following a literature-reported method carried out in N,N-dimethylformamide (DMF) as reaction medium, resulting in phosphorus-containing PVA networks (PVA-OP3). Hybrid gel-like films were then prepared by incorporating titanium dioxide nanoparticles (TiO₂ NPs), known for their antimicrobial activity, low toxicity, and high stability. The resulting composites were structurally, morphologically, and thermally characterized using FTIR, SEM, and thermogravimetric analysis. The incorporation of TiO₂ NPs significantly improved the thermal stability, with T₅% increasing from 240 °C for neat PVA-OP3 to 288 °C for the optimal composite, increased the char residue from 4.5% for the neat polymer to 30.1% for PVA-OP3/TiO₂-4, and enhanced antimicrobial activity against both Gram-positive and Gram-negative bacteria. These findings demonstrate that PVA-OP3/TiO₂ hybrid films possess promising potential as advanced biomaterials for biomedical, protective, and environmental applications. Full article

As an eco-friendly flame-retardant additive, magnesium hydroxide (MH) is widely employed in low-smoking, halogen-free polymer materials due to its environmentally benign nature. In order to enhance flame retardancy performance, the modified MH was modified with tetrakis(hydroxymethyl)phosphonium sulfate (THPS) by a one-pot hydrothermal method. The resulting morphology was characterized using scanning electron microscopy (SEM), and it shows the dispersion of nanometer particles and almost no aggregation. The X-ray photoelectron spectroscopy (XPS) along with Raman spectroscopy show that the THPS is connected with the Mg(OH)₂ by chemical bond. The sample was incorporated into ethylene–vinyl acetate (EVA) to evaluate the flame retardancy was assessed via limiting oxygen index (LOI) and vertical burning tests (UL-94). The results show that THPS modified MH effectively enhanced the flame retardancy, achieving a V-0 rating and an LOI value of 31.3%. In addition, the composites retain good mechanical integrity. The thermal analysis with TGA and DTG shows the formation of the MgO decomposition product, along with water vapor and phosphorus-containing radicals released by modified MH in the combustion process, forming a strong flame-retardant protective layer. In addition, the maximum smoke density of EVA/MHP-3 composite was 155.4, lower than 411.3 for EVA/MH, with a 62.2% reduction in total smoke production. The result shows that THPS is effective for improving the flame-retardant efficiency of inorganic metal hydroxide in polymer composites. Full article

This review examines the fire-retardant properties of compositions that incorporate various classes of phosphorus–nitrogen compounds. Specifically, it focuses on nitrogen-containing derivatives of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phosphinates, phosphorus–nitrogen salts, and aryloxycyclophosphazenes. The findings indicate that these classes of fire retardants enhance the limiting oxygen index, decrease heat and smoke emission indices in epoxy compositions, and facilitate the creation of self-extinguishing materials. Notably, aryloxycyclophosphazenes with reactive functional groups emerge as the most effective fire retardants, particularly in terms of their impact on the mechanical properties of epoxy compositions and compatibility with epoxy resin. This review would be a valuable resource for engineers, chemical engineers, materials scientists, and researchers engaged in the development of non-combustible polymer composites and organoelement compounds. Full article

Background: The aim of this study was to investigate the radioprotective efficacy of polymer complexes constructed from amifostine (WR-2721) and poly(hydroxyoxyethylene phosphate)s with different molecular weights. The use of suitable polymers for the immobilization of radioprotective drugs is aimed at improving or obtaining important new properties. Methods: The radioprotective efficacy of the compounds was investigated by cytotoxicity and the survival of mouse embryonic fibroblasts MEF LIG4^+/+ and MEF LIG4^−/− cells irradiated with 2, 6 and 12 Gy in the presence of amifostine (WR-2721) and its polymer complexes. Results: The radioprotective efficacy of the polymer complexes constructed of amifostine (WR-2721) and poly(hydroxyoxyethylene phosphate)s with different molecular weights showed promising activity and dose regimens. Conclusions: Cytotoxicity studies for tested cell lines MEF LIG4^+/+ and MEF LIG4^−/− cells showed that the polymer complexes were not toxic when equivalent doses of the drug amifostine (WR-2721) were applied to the cells. Irradiated MEF LIG4^+/+ cells demonstrated an increase in the surviving fraction when pre-treated with 0.5–5 mM polymer complexes when equivalent doses of amifostine (WR-2721) were applied to the cells and irradiated. The radioprotective efficacy had increased when the cells MEF LIG4^+/+ were irradiated with 12 Gy. These findings demonstrate that poly(hydroxyoxyethylene phosphate)s are suitable carriers of the radioprotective drug amifostine (WR-2721). They further suggest that they may be interesting for researchers seeking new challenges in discovering advanced radioprotective active substances. Full article

Flammability is a significant challenge in polymer-based strain sensing applications. In addition, the existing intrinsic flame retardant is not elastic at room temperature, which may potentially damage the flexible equipment. This study presents a series of flame-retardant ionic conductive elastomers (ICEs) (denoted as PCAIP_x) containing phosphorus from phytic acid (PA) and nitrogen from choline chloride (ChCl) with multiple hydrogen bonds synthesized using a simple and efficient one-pot UV-initiated radical copolymerization of a polymerizable deep eutectic solvent (PDES). The limiting oxygen index (LOI) value increased from 24.1% for the pure PCAI without PA to 38.3% for PCAIP_7.5. The SEM analysis of the residual char shows that the formation of the dense and continuous char layer effectively worked as a shield, preventing further decomposition of the undecomposed polymer inside while hindering the transmission of heat and mass and isolating the oxygen required for combustion. The hydrogen bonds’ cross-linked structure and phosphorus-containing elastomer demonstrate a superior elasticity (elongation at break of up to 2109%), durability, and tear resistance and excellent adhesive properties. Application of PCAIP_X in strain sensors showed that the elastomer has excellent cyclic stability and exhibited repeatable and stable resistance change signals in response to repetitive bending motions of the wrist, fingers, elbow, and knee. Consequently, this study provides a simple strategy for the development of a flame-retardant ICE which can effectively reduce fire hazards and potentially be applied in other fire-risk fields such as personal protection, firefighting, and sports equipment. Full article

An effective type of polymer heat-insulating material (foams) based on reactive oligomers is casting epoxy foams with high technological and operational parameters. However, polyepoxide foams are highly flammable, which significantly restrains their application in the construction industry. The aim of this work was to develop effective methods for reducing the flammability of filling epoxy foams. In order to achieve the objective, the following objectives were addressed: determining the influence of the chemical nature and content of additive and reactive bromine- and phosphorus-containing compounds on the thermal stability, flammability and operational properties of filling epoxy foams, and the development of polyepoxy foams of reduced flammability with high-quality physical and mechanical characteristics. When estimating the flammability of epoxy foams, we used both state-approved methods and the methods described in scientific and technical literature. The thermal properties of epoxy foams were studied with the help of multimodular thermoanalytical complex DuPont-9900. The data on the influence of the apparent density of foams and oxygen concentration in the oxidant flow on the flame propagation speed on the horizontal surface of polyepoxy foams are presented. It was revealed that the chemical nature of amine hardeners does not affect the thermal stability and flammability of epoxy foams. It was established that phosphate plasticizers are ineffective flame retardants of foamed epoxy resin, and the chemical structure of additive organobromic flame retardants insignificantly affects their efficiency. It was shown that microencapsulated flame retardants are inferior in flame retardant efficiency to additive flame retardants. It was found that effective flame retardants for casting polyepoxy foams are phosphorus-containing oligoether methacrylate and epoxidized waste from the production of tetrabromodiphenylpropane. The results of this research will form the basis for the production of an experimental industrial batch of samples of pouring epoxy foams of reduced flammability. Full article

This article presents the results of research on the development of chemically resistant polymer–mineral casting composites based on industrial waste. The aim of this work is to develop a technological basis for obtaining effective inorganic fillers and highly filled composites for use in chlorine-containing environments. On the basis of theoretical data, mineral fillers and a polymer binder for filling composites were selected, optimal quantities of input hardeners and an appropriate thermal curing mode were determined, and the influence of the filling degree on the properties of composites was studied. The influence of various factors on the properties of the obtained composites was also studied, and the possibility of using local raw materials to obtain special-purpose composites was investigated. Ash from a thermal power plant (TPP) was used as an acid-resistant filler in composites. Two components were chosen as binders: phenol formaldehyde resin and mineral filler (TPP ash). As the third component, hydrolytically active fillers—anhydrite, phosphogypsum and phosphate slag—were used. The degree of filling has a significant influence on the properties of composites, including the compressive strength, chemical resistance and degree of curing, the values of which were elucidated across a wide range of composite variations based on the degree of filling. The conducted research allowed us to establish the limit of admissible anhydrite content, which should not exceed 15 mas.%. To optimize the chemical resistance and durability of the composites of the investigated substances, the method of mathematical planning was used. According to the results of this study, the optimal compositions of composites, in terms of anhydrite, phosphogypsum and phosphorus slag contents, were selected. At the maximum possible degree of filling, these composites exhibit high target characteristics. Full article

Starting from poly(4-vinylpyridine) ((P4VP)_n), poly(2-vinylpyridine) ((P2VP)_n), and [N=P(O₂CH₂CF₃)]_m-b-P2VP₂₀ block copolymers, a series of metal-containing homopolymers, (P4VP)_n⊕MX_m, (P2VP)_n⊕MX_m, and [N=P(O₂CH₂CF₃)]_m-b-P2VP₂₀]⊕MX_m MX_m = PtCl₂, ZnCl₂, and Eu(NO₃)₃, have been successfully prepared by using a direct and simple solution methodology. Solid-state pyrolysis of the prepared metal-containing polymeric precursors led to the formation of a variety of different metallic and metal oxide nanoparticles (Pt, ZnO, Eu₂O₃, and EuPO₄) depending on the composition and nature of the polymeric template precursor. Thus, whereas Eu₂O₃ nanostructures were obtained from europium-containing homopolymers ((P4VP)_n⊕MX_m and (P2VP)_n⊕MX_m), EuPO₄ nanostructures were achieved using phosphorus-containing block copolymer precursors, [N=P(O₂CH₂CF₃)]_m-b-P2VP₂₀]⊕MX_m with MX_m = Eu(NO₃)₃. Importantly, and although both Eu₂O₃ and EuPO₄ nanostructures exhibited a strong luminescence emission, these were strongly influenced by the nature and composition of the macromolecular metal-containing polymer template. Thus, for P2VP europium-containing homopolymers ((P4VP)_n⊕MX_m and (P2VP)_n⊕MX_m), the highest emission intensity corresponded to the lowest-molecular-weight homopolymer template, [P4VP(Eu(NO₃)₃]₆₀₀₀, whereas the opposite behavior was observed when block copolymer precursors, [N=P(O₂CH₂CF₃)]_m-b-P2VP₂₀]⊕MX_m MX_m= Eu(NO₃)₃, were used (highest emission intensity corresponded to [N=P(O₂CH₂CF₃)]₁₀₀-b-[P2VP(Eu(NO₃)₃)_x]₂₀). The intensity ratio of the emission transitions: ⁵D₀ → ⁷F₂/⁵D₀ → ⁷F₁, suggested a different symmetry around the Eu³⁺ ions depending on the nature of the polymeric precursor, which also influenced the sizes of the prepared Pt°, ZnO, Eu₂O₃, and EuPO₄ nanostructures. Full article

Short flax fibers have been modified by radiation-induced grafting using methacrylate monomers containing phosphorus to give them a flame-retardant character. Two methodologies, namely pre-irradiation and simultaneous irradiation grafting, were examined. Certain parameters, notably the dose and the irradiation source (e-Beam and γ rays), were evaluated. The grafting efficiency, in terms of phosphorus content (mass percentage), was measured by X-ray fluorescence spectrometry (XRF). Using simultaneous irradiation, 2.39 wt% phosphorus could be obtained from 10 kGy, compared to 100 kGy in pre-irradiation. Furthermore, for similar phosphorus levels, the location of the grafted polymer chains was different for the two methodologies. The effect of phosphorus content on thermal properties and fire behavior was evaluated on a microscopic scale using a pyrolytic flow combustion calorimeter (PCFC) and on a laboratory scale using a cone calorimeter. It was then pointed out that flammability was linked to the phosphorus content and likely its location, which is associated with the radiation-induced grafting methodology, showing that the grafting conditions influence the final fire properties. Simultaneous irradiation, thus, proved to be more interesting in terms of efficiency and final properties. Full article